When I click "Scan for my stash" via the world-map, all my available stashes in the area appear on the map. However, when I hover over my stash and attempt to right-click it for actions the wow interface overrides it, causing my map to just zoom out instead. I looked online for a way to disable the right-click zoom out setting but it seems it is not possible. Nor could I find any addons to change this.

Is there a fix for this?

There was indeed an API change that was fixed in the base addon but not in Extended, I'll have the fix shipped for 11.1.7.